What is a polarizing microscope
A polarizing microscope is a type of microscope used to study so-called transparent and opaque anisotropic materials. All substances with birefringence can be clearly distinguished under a polarizing microscope. Of course, these substances can also be observed by staining, but some are impossible, and a polarizing microscope must be used.
(1) Characteristics of polarized light microscopes
A method of changing ordinary light into polarized light for microscopic examination to identify whether a substance is single-refractive (isotropic) or birefringent (anisotropic). Birefringence is a fundamental property of crystals. Therefore, polarized light microscopy is widely used in the fields of minerals, chemistry, etc., and also has applications in biology and botany.
(2) The basic principle of polarized light microscope
The principle of polarizing microscope is more complicated, so I won't introduce it too much here. Polarizing microscope must have the following accessories: polarizer, analyzer, compensator or phase plate, special stress-free objective lens, and rotating stage.
(3) The method of polarizing microscopy
a. Orthscope: also known as distortion-free microscopy, which is characterized by the use of a low-magnification objective lens without Bertrand Lenses, and the object to be studied can be directly studied with polarized light. At the same time, in order to make the illumination aperture smaller, the upper lens of the condenser is pushed away. Normal phase microscopy is used to examine the birefringence of an object.
b. Conoscope: Also known as interference microscopy, it studies the interference pattern generated when polarized light interferes. This method is used to observe the uniaxial or biaxiality of an object. In this method, the illumination is performed with a strongly converging polarized light beam.
(4) Requirements on the installation of polarized light microscopes
a. Light source: It is best to use monochromatic light, because the speed of light, refractive index, and interference phenomena are different due to different wavelengths. General microscopy can use ordinary light.
b. Eyepieces: Eyepieces with crosshairs.
c. Condenser: In order to obtain parallel polarized light, a swing-out condenser that can push out the upper lens should be used.
d. Bertrand lens: an auxiliary component in the optical path of the condenser, which is an auxiliary lens that magnifies the primary phase caused by the object into the secondary phase. It guarantees the observation with the eyepiece of the flat interference pattern formed in the rear focal plane of the objective.
(5) Requirements for polarizing microscopy
a. The center of the stage is coaxial with the optical axis.
b. The polarizer and analyzer should be in orthogonal position.
c. The film should not be too thin.
